Tamper evident container and closure

ABSTRACT

A container and a closure for the container are disclosed. The container has a projection extending outwardly from a sidewall that surrounds a central space. The projection is received within a channel having inner and outer legs that form a perimeter of the closure. The projection engages an inwardly projecting shoulder formed by a lip attached to the outer channel leg. The lip is removable to allow removal of the closure from the container. The lip serves a tamper-evident function. The projection takes the form of a flange arranged at an acute angle or a rib formed of reverse folded sidewall portions. A method of forming the container is also disclosed. A first sidewall portion having a free edge is folded over and attached to a second sidewall portion adjacent the free edge.

FIELD OF THE INVENTION

This invention relates to containers formed of paperboard and closures therefor having a tamper evident feature.

BACKGROUND OF THE INVENTION

Paperboard containers having a rolled edge surrounding the container's opening find widespread use throughout industry for the packaging of bulk materials and foodstuffs, especially dairy related products such as butter, yogurt and ice cream. Paperboard as a material for containers provides various advantages as it is inexpensive, is easily formed into various shapes, can be conveniently imprinted to display colorful and attention getting advertising and trademark indicia and is compatible with various coatings and adhesives.

While the rolled edge provides a convenient and simple rim that engages a closure and renders the container resealable after its initial opening, a distinct disadvantage of such an edge is its inability to cooperate effectively with a tamper evident closure. Tamper evident closures, for example, composite closures formed from a paperboard panel surrounded by a plastic skirt, typically use a tear-away strip formed along the bottom of the skirt. Normally the closure cooperates with the container and cannot be removed unless the tear-away strip is first removed from the skirt. The absence of the tear-away strip indicates that the container has been previously opened and provides evidence of possible tampering with the contents of the container.

However, when a tamper evident closure having a tear-away strip is placed on a container having a rolled edge, the closure can be easily removed without removing the tear-away strip. This is because the rolled edge is flexible and therefore easily deformed, and as the rolled edge is engaged by the strip, it simply unrolls, thereby allowing the removal of the closure and thwarting the tamper evident feature.

There is clearly a need for a paperboard container that cooperates with a tamper evident closure so that the advantages of both components may be realized.

SUMMARY OF THE INVENTION

The invention concerns a container for containing foodstuffs and the like. The container has a tamper evident feature and comprises a bottom and a sidewall surrounding the bottom. The sidewall defines a central space and has a free edge surrounding an opening positioned opposite to the bottom. A projection extends outwardly from the sidewall adjacent to the opening. The projection is formed by a first sidewall portion contiguous with the free edge that is reverse folded into overlying relation with a second sidewall portion adjacent to the free edge. The first and second sidewall portions are attached to one another thereby stiffening the sidewall surrounding the opening.

In one embodiment, the projection comprises a flange oriented at an acute angle relatively to the sidewall. In another embodiment, the projection comprises a rib attached to an outer surface of the sidewall.

The invention also includes a closure for use with the container. The closure comprises a panel positionable overlying the opening. A channel forms a perimeter surrounding the panel. The channel has an inner leg, and an outer leg in spaced relation to the inner leg. The projection on the container is positionable between the inner and outer legs when the panel is positioned overlying the opening. A lip is positioned on the outer leg. The lip is separable from the outer leg and has a shoulder that projects toward the inner leg. The shoulder is engageable with the projection and prevents removal of the closure from the container. The closure is removable upon separation of the lip from the outer leg.

The invention also includes a method of forming a container. The method comprises:

(a) attaching a sidewall surrounding a bottom thereby defining a central space and an opening, the sidewall having a free edge surrounding the opening;

(b) folding a first sidewall portion contiguous with the free edge into overlying relation with a second sidewall portion adjacent to the free edge;

(c) attaching the first and second sidewall portions to one another; and

(d) folding the first and second sidewall portions outwardly away from the opening.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a perspective view of a container and closure according to the invention;

FIG. 2 is a partial perspective view of a portion of the container shown in FIG. 1;

FIG. 3 is a partial sectional view illustrating the formation of the container shown in FIG. 1;

FIGS. 4 and 5 are perspective views of additional embodiments of the container and closure according to the invention;

FIG. 6 is a partial sectional view of a portion of the container and closure shown in FIG. 1;

FIG. 7 is a partial sectional view showing another embodiment of a container and closure according to the invention; and

FIGS. 8 and 9 are a partial sectional views illustrating the formation of an embodiment of a container according to the invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

FIG. 1 shows a container 10 and its closure 12 according to the invention. Container 10 has a bottom 14 and a sidewall 16 that surrounds a central space 18. The container has an opening 20 providing access to the central space 18. A projection 22, shown in detail in FIG. 2, extends outwardly from the sidewall adjacent to the opening 20.

In the embodiment shown in FIGS. 1 and 2, the projection comprises a flange 23 that is oriented at an acute angle 24 with respect to the sidewall 16. Preferably, the projection 22 is formed as shown in FIG. 3, by reverse folding a first portion 26 of sidewall 16 into overlying relation with a second portion 28 of the sidewall and then attaching the first and second portions together. The first sidewall portion 26 is contiguous with a free edge 27 of the sidewall, and the second sidewall portion 28 is adjacent to the free edge.

Attachment of the sidewall portions to one another is preferably accomplished by coating the sidewall portions with a polymer layer 29, such as polyethylene or polypropylene. Heated jaws 30 of a forming machine (not shown) are then applied to compress the sidewall portions together and melt the polymer layer. The layer 29 cures and fuses the sidewall portions 26 and 28 to one another. By angling the contact faces of jaws 30, the desired acute angle 24 between the flange 23 and the sidewall 16 that is characteristic of this profile may be set. Alternately, adhesive may also be used to attach the sidewall portions together and form the outwardly extending projection 22.

The projecting flange 23 may be used on any shape container including rectangular containers 10 having rounded corners 11 as shown in FIG. 1, or round containers 13 shown in FIG. 4. The flange 23 may be substantially continuous around the entire opening 20, or several flanges may be confined to discrete regions of the container, such as at the rounded corners 11 of the rectangular container 15 as shown in FIG. 5.

FIG. 1 also shows a closure 12 according to the invention. Closure 12 is preferably a composite construction comprising a central panel 32 formed of paperboard surrounded by a channel 34 made of plastic such as polypropylene or polyethylene. Channel 34 forms a perimeter of closure 12. As best shown in FIG. 6, channel 34 comprises a downwardly oriented inner leg 36 and a downwardly oriented outer leg 38 positioned in spaced apart relation from the inner leg. When closure 12 is positioned overlying opening 20, the inner leg 36 engages the container sidewall 16 and the outer skirt 38 engages the projection 22, the projection being captured within the channel 34 between the inner and outer legs.

As further shown in FIG. 6, closure 12 includes a lip 40 attached to the outer leg 38. Lip 40 has a shoulder 42 that projects inwardly toward the inner leg 36 so as to engage the projection 22 and prevent removal of the closure from the container as long as it is present. Removal of the closure is prevented because the projection 22 is stiff in transverse shear, being attached sidewall portions forming a flange 23 that cannot “unroll” as would occur for a rolled edge, and because the flange is captured at an acute angle 24 between the legs 36 and 38 and the shoulder 42. The projection 22, when formed as the flange 23, thus acts as a barb retaining the closure to the container when tensile force is applied. The legs 36 and 38 do not permit the flange to rotate about its point of attachment 44 to the sidewall, the projection 22 jamming itself within the channel. 34 and effectively preventing removal of the closure 12 from the container. Removal of lip 40, however, eliminates the shoulder 42 and permits the ready removal of the closure. Lip 40 is therefore preferably attached to outer skirt 38 by a weakened region 46 of reduced thickness to permit manual removal from the outer leg 38 when it is desired to open the container. Lip 40, thus acts as a tamper evident feature, its absence indicating that the container 10 may have been opened.

For containers having a round cross section as shown in FIG. 4, the flange 23 and lip 40 will be most effective if they extend completely and continuously around the container and the closure respectively. However, for containers having a rectangular cross section with rounded corners as shown in FIG. 5, the flange 23 and lip 40 must at least be at the corner portions of the container to be effective.

Another container embodiment 48 is illustrated in FIG. 7. In container 48, a rib 50 extends outwardly from the sidewall 16. Rib 50 engages lip 40 which, as previously described, is removably attached to outer leg 38 of closure 12, the lip having an inwardly projecting shoulder 42 that provides the contact between the lip and the rib. The outer leg 38 engages the rib 50 and the inner leg 36 again engages the sidewall 16 of the container.

FIGS. 8 and 9 illustrate one method of forming rib 50. As shown in FIG. 8, the sidewall 16 around the opening 20 of container 48 is first rolled outwardly and back upon itself forming a rolled edge 52 surrounding the container's opening. Next, as shown in FIG. 9, heated jaws 54 of a forming machine (not shown) are applied to the rolled edge 52 to fold a first sidewall portion 56 into overlying relation with a second sidewall portion 58 to form the rib 50. Jaws 54 also fold a third sidewall portion 60 contiguous with rib 50 into overlying relation with an outer surface 62 of sidewall 16 forming a particular profile shape. Again, the sidewall 16 of container 10 is coated with a polymer layer 29 such as polypropylene or polyethylene which melts and fuses to seal the rolled rim into the rib 50 and the desired profile shape determined by the shape of the jaws. Other profiles are also feasible for forming the projection depending upon the shape of the jaws and the initial manner of forming the edge, which could initially be angular, or rounded as shown. Fusing the rib stiffens the sidewall surrounding the opening of the container and prevents the closure from being removed without first removing the tamper evident lip.

Containers having sealed profiled edges as disclosed allow paperboard containers to take advantage of tamper evident features on composite closures, providing increased security against tampering over rolled edges that are not sealed profiled edges. 

1. A container comprising: a bottom; a sidewall surrounding said bottom and defining a central space, said sidewall having a free edge surrounding an opening positioned opposite to said bottom; and a projection extending outwardly from said sidewall adjacent to said opening, said projection being formed by a first sidewall portion contiguous with said free edge reverse folded into overlying relation with a second sidewall portion adjacent to said free edge, said first and second sidewall portions being attached to one another.
 2. A container according to claim 1, wherein said projection comprises a flange oriented at an acute angle relatively to said sidewall.
 3. A container according to claim 2, wherein said sidewall defines a circular cross section.
 4. A container according to claim 3, wherein said flange extends entirely around said opening.
 5. A container according to claim 2, wherein said sidewall defines a substantially rectangular cross section having rounded corners.
 6. A container according to claim 3, wherein said flange extends entirely around said opening.
 7. A container according to claim 5, wherein a flange is positioned at each of said corners.
 8. A container according to claim 1, further comprising a polymeric layer positioned between said first and second sidewall portions, said polymeric layer being fusible so as to adhere said first and second sidewall portions to one another upon the application of heat and pressure to said sidewall portions.
 9. A container according to claim 8, wherein said polymeric layer is a material selected from the group consisting essentially of polypropylene, polyethylene, and combinations thereof.
 10. A container according to claim 1, further comprising an adhesive layer positioned between said first and second sidewall portions, said adhesive layer adhering said first and second sidewall portions to one another.
 11. A container according to claim 1, wherein said projection comprises a rib attached to an outer surface of said sidewall and facing outwardly therefrom.
 12. A container according to claim 11, wherein said rib comprises said first and second sidewall portions folded into overlying relation with and attached to one another, and a third portion of said sidewall contiguous with said rib folded outwardly at said opening into overlying relation with said outer surface of said sidewall.
 13. A container according to claim 11, wherein said sidewall defines a circular cross section.
 14. A container according to claim 13, wherein said flange extends entirely around said opening.
 15. A container according to claim 11, wherein said sidewall defines a substantially rectangular cross section having rounded corners.
 16. A container according to claim 15, wherein said flange extends entirely around said opening.
 17. A container according to claim 15, wherein a flange is positioned at each of said corners.
 18. A container according to claim 1, further comprising: a closure adapted to close said opening, said closure comprising: a panel positionable overlying said opening; a channel forming a perimeter surrounding said panel, said channel having an inner leg and an outer leg in spaced relation to said inner leg, said projection being positionable between said inner and outer legs when said panel is positioned overlying said opening; and a lip positioned on said outer leg, said lip being separable from said outer leg and having a shoulder projecting toward said inner leg, said shoulder being engageable with said projection and preventing removal of said closure from said container, said closure being removable upon separation of said lip from said outer leg.
 19. A container according to claim 18, wherein said panel is formed from paperboard and said channel and said lip are formed from a polymer attached to said panel.
 20. A closure for a container having a sidewall surrounding an opening and a projection extending outwardly from said sidewall adjacent to said opening, said closure comprising: a panel positionable overlying said opening; a channel forming a perimeter surrounding said panel, said channel having an inner leg and an outer leg in spaced relation to said inner leg, said projection being positionable between said inner and outer legs when said panel is positioned overlying said opening; and a lip positioned on said outer leg, said lip being separable from said outer leg and having a shoulder projecting toward said inner leg, said shoulder being engageable with said projection and preventing removal of said closure from said container, said closure being removable upon separation of said lip from said outer leg.
 21. A container according to claim 20, wherein said panel is formed from paperboard and said channel and said lip are formed from a polymer attached to said panel.
 22. A method of forming a container, said method comprising: attaching a sidewall surrounding a bottom thereby defining a central space and an opening, said sidewall having a free edge surrounding said opening; folding a first sidewall portion contiguous with said free edge into overlying relation with a second sidewall portion adjacent to said free edge; attaching said first and second sidewall portions to one another; and folding said first and second sidewall portions outwardly away from said opening. 